We propose to use ion-beam patterning of plasmonic nanoparticles made by standard electron beam lithography, plasmonic metal deposition, and lift-off sequence. With this approach new three-dimensional (3D) tailoring of nanoparticles becomes possible: cut through the particle and into the substrate, cut-through at an angle, trim or bore nanoparticles or substrate. Here, we numerically simulate the expected optical properties of such 3D patterned nanoparticles. We show a particular case when spectrally broad extinction band can be created with a strong light field enhancement on a Si substrate. Nanoparticles with a 10-20 nm nano-gap cut by ion-beam at the chosen location and to the required depth into the substrate. Scanning electron microscopy (SEM) image of the fabricated Au-nanoparticles.